The only exterior difference between a regular RX 400 and a hybrid is the small 'h' on the rear nameplate.

2006 Lexus RX 400h Hybrid Preview

Quad-power hybrid SUV gets up and goes

By Bill Roebuck

May 4, 2005 -- When you look at the fuel economy numbers for any vehicle, the lowest consumption is always at highway speeds. But the tables are turned for the latest offering from Lexus. Its city mileage is slightly better than its highway rating.

That's because the new Lexus RX 400h is a hybrid. In fact, it is the first luxury SUV in the world to include both gasoline and electric engines.

That makes the new sport-ute achieve the same kind of fuel economy as an average compact sedan, and also reduces emissions so they meet SULEV (Super Ultra Low Emissions Vehicle) and Tier 2/Bin 3 criteria.

The all-wheel drive 400h is not just a typical hybrid; it has four motors in all -- a standard gas-driven V6 and three electrics.

"The newest RX is a full hybrid," says Stuart Payne the company director responsible for Lexus in Canada. That means it is capable of operating in separate gasoline or electric modes, as well as combining power from both. (Some hybrid technologies are partial, using an electric motor as a starting aid and not for propulsion).

What's interesting about the 400h is that although it is powered by the same 3.3-litre V6 engine as in the similarly designed Lexus RX 330, it uses the electric motors as a boost to give V8-like performance.

Compared to the 330's 208 hp, the 400h delivers 268. It accelerates from zero to 100 km/h in under eight seconds.

Average city/highway fuel economy is 7.5/8.1 L/100 km in the 400h, compared to the gas-powered RX 330's rating of 12.8/9.1 L/100 km. "Our hybrid system is more efficient that current fuel cell vehicles," says Lexus Canada spokesman Jeff Powell.

Here's another interesting design element. The electric motor that drives the rear wheels in all-wheel drive mode is not connected mechanically to the front drive.

This SUV also features a fuel-saving continuously variable transmission (CVT), so there's no noticeable sensation of gear changes.

The Lexus system is called Hybrid Synergy Drive (HSD). It uses a 123-kilowatt front drive electric motor operating at up to 650 volts. It produces a peak torque of 262 lb-ft from 0 to 1,500 rpm. A 50-kilowatt rear-drive motor, using a newly designed reduction gear, develops a peak torque of 96 lb-ft from 0 to 610 rpm. A third electric motor is used for starting and acts as a generator.

As in other full hybrid designs, regenerative braking us used to boost the system's efficiency. When the vehicle is coasting or the brakes are applied, the electric motor functions as a generator, recharging the battery. Because of this, you never have to plug in a hybrid vehicle.

When I drove the RX 400h recently, even on hills there was no way to tell when the electric motors were called to action. It basically runs just like the gasoline powered RX 330.

There are a few differences between the 330 and the 400h, though. The hybrid has a longer nose to accommodate the extra air intake required for cooling the batteries. Its front grille also has been redesigned slightly.

There also is a tiny bit less headroom in the hybrid's rear seat because the batteries are stored under it. They are constantly cooled from air within the cabin, so the seats don't warm up.

If you listen carefully while driving the hybrid, you can hear a slight whine from the motors when you're coasting or braking as they turn into generators, with the sound appearing to come from the rear, under the cargo area. All noises disappear when you come to a stop, as the gas engine shuts off temporarily.

The only other noticeable difference inside is the lack of a tachometer. It's replaced by a power meter that displays the level of power generated by the hybrid powertrain. You can monitor the power distribution continually on models equipped with a touch-screen display, although it distracts your eyes from the road.

Although the RX 400h carries a price premium of about $6,000 over an RX 330, you get more than just the added hybrid technology for your money. The 400h also is equipped with a Vehicle Dynamics Integrated Management (VDIM) advanced stability system.

VDIM continuously analyzes driver inputs such as steering, braking, acceleration and deceleration and compared it to a desired, stable operation. If there's a difference between the two, the system enhances braking or engine output to stabilize the situation.

As well, the 400h has unique 18-in. alloy wheels, electrically powered air conditioning, electronic brake control and electric power steering.

Lexus expects the hybrid will boost sales of its RX line by 15%. The Premium RX 400h is priced at $62,200, and the Ultra Premium model, which includes an upgraded stereo, DVD entertainment/navigation systems and more, is $69,700.

Sales tax rebates are offered for hybrid vehicles sold in Ontario ($1,000), B.C. ($2,000) and P.E.I. (up to $3,000). Hybrids also are exempt from emissions testing in Ontario.

It's noteworthy that the hybrid Lexus is not designed to show off its environmentally friendly breeding. Aside from the subtle design changes, a small 'h' on the nameplate is the only external clue to the powertrain's technology.

"We expect customers will buy it to impress themselves, not their neighbours," says Payne.